This invention relates to piston pumps and compressors, and more particularly to a connecting rod with an integral grease reservoir for use in piston pumps and compressors.
Small-scale air compressors are often used to power nebulizers. A typical type of compressor for that purpose uses a wobble piston. Examples of such compressors are found in U.S. Pat No. 3,961,868, issued Jun. 8, 1976 to Arthur J. Droege, Sr. et al, for "Air Compressor" and U.S. Pat. No. 4,842,498, issued Jun. 27, 1989 to Roy J. Rozek, for "Diaphragm Compressor".
In a typical compressor, a piston reciprocates in a cylinder sleeve to compress air. The piston is a plastic connecting rod having a piston end disposed in the cylinder sleeve, and a connecting end connected to an eccentric component mounted to a shaft. As the shaft rotates, the connecting rod having a piston head disposed in a cylinder sleeve reciprocates to compress air. In one prior art compressor, the connecting rod end includes a ball bearing as the interface between the rod and the eccentric component. In another form of prior art, the rod does not include a ball bearing. Instead, a pin projecting from the eccentric component is slidably inserted into a bore formed in the connecting end. This design relies on the free rotation of the pin within the bore.
The bore is preferably formed to have an interior diameter which is substantially equal to the outside diameter of the pin to avoid chatter. Some form of lubrication is provided in this assembly to enhance the life of the bore. The lubrication method typically used includes an oil saturated felt wick that makes contact with the side of the pin, this contact occurring though a small hole in the side of the rod end. Lubrication of the bore occurs by means of capillary action drawing oil from the wick, into the bore. This design concept has proved unreliable due to problems with drying of the wick, wick becoming dislodged during operation, or poor capillary lubrication. Therefore, a need existed for a means to easily assemble and reliably lubricate the pin within the bore.